Irradiation method and apparatus



y 31,1960 7 R. c. GORDON ETAL 2,938,804

IRRADIATION METHOD AND APPARATUS Filed Sept. 13, 1957 6 Sheets-Sheet 1May 31, 1960 R. c. GORDON ET AL 2,938,804

IRRADIATION METHOD AND APPARATUS 6 Sheets-Sheet 2 Filed se i. 15, 1957Qm w May 31, 1960 R. c. GORDON ETAL 2,938,804

IRRADIATION METHOD AND APPARATUS 6 Sheets-Sheet 3 Filed Sept. 13, 1957May 31, 1960 R. c. GORDON ET AL 2,938,804

IRRADIATION METHOD AND APPARATUS Filed Sept. 13, 1957 6 Sheets-Sheet 4IN V EN TORS o zafl/ Alley May 31, 1960 R. c. GORDON ET AL 2,938,804

IRRADIATION METHOD AND APPARATUS 6 Sheets-Sheet 5 Filed Sept. 13, 1957 Ii v o l l O INVENTORS.

1, 1960 F c. GORDON ETAL 2,938,804

IRRADIATION METHOD AND APPARATUS 6 Sheets-Sheet 6 Filed Sept. 13, 1957yore. r: \Q/ndwzwzgk United States Patent IRRADIATION IVIETHOD ANDAPPARATUS Roy C. Gordon, Oak Lawn, and Bertie S. Harrington,

Chicago, 111., assignors to Armour and Company, Chicago, Ill., acorporation of Illinois Fiied Sept. 13, 1957, Ser. No. 683,776

14 Claims. (Cl. 99-217) The present invention relates to a method andapparatus for the irradiation of substances. A

Two Significant problems have been encountered by those working in thefield of cold sterilization of foodstuffs. One has been the productionof unwanted color and flavor changes in the product. The other has beenthe problem of obtaining a sufficient quantity of high speed beta rays,etc., to kill the bacteria without excessive periods of irradiation. Theprincipal object of the present invention is directed to the abatementof these problems.

Radiation equipment, other than that using natural sources of radiation,usually employs a tube in which the electrons, etc., are accelerated.Such tubes have a window at one end through which electrons are emittedfor use in the irradiation process, but windows have recognizeddisadvantages. In the first place the window will absorbsome of theradiant energy; the thicker the window the more radiant energy Will beabsorbed therein.

This reduces the energy output of the tube and the heat produced by theabsorption of the radiant energy must be dissipated. Secondly thewindows are often punctured by the radiant energy necessitating ashutting down of the equipment and a replacement of the windows. Afterthe window has been replaced the tube must be re-evacuated before theequipment again can be used.

Various proposals have been made from time to time seeking to solve thisproblem, for example, some workers in the field have contemplated theuse of readily movable windows so that a new window surface may beprovided quickly and without complete release of the vacuum when awindow has been punctured. Other efforts directed towards the use oflighter weight windows contemplate provide a method and apparatus bywhich the efiiciency of such radiation equipment can be increased interms of electron output beyond the tube as compared to the quantity ofelectrons actually produced Within the tube. In the present inventionthis is done by maintaining air pressures beyond the end of the tubesubstantially equal to the air pressure within the tube. Equivalent airpressures are maintained at all times so that at no time is there agreat pressure difierential beyond the tube and within the tube. Thispermits much lighter weight windows and also if a window fails, it ismuch easier to replace it with a mechanical transport, etc., ascontemplated by the prior art (see for example Patent 2,617,953), and tore-establish the proper vacuum conditions within the tube.

The second facet of the principal object of the inven-' ice tion is theelimination of ozone about the product without the necessity ofresorting to special packaging proceedures. It has been recognized thatozone was at least one of the factors that resulted in the production ofundesirable flavor and color changes when foodstuffs were irradiated.The prior art has suggested the use of special vacuum packages so thatthere would be a negligible amount of oxygen present about the productto be converted into ozone. Not only are many cuts of meat, etc.,particularly irregularly shaped objects, dificult and expensive tovacuum package, but the package itself further reduces the amount ofradiation that reaches the product. Through the use of our invention itis not necessary to vacuum package the product in order to achieve thesame reductionin the ozone present about the product when it isirradiated.

The present invention also eliminates any danger of harm to workerscarrying out the irradiation of substances which otherwise might resultfrom excessive contact with ozone. Not only is there very little oxygenpresent at the end of the radiation tubes to be converted into ozone,but the radiation is all carried out in a confined space into which theworkers are not required to go so that there is no opportunity for themto come into contact with the little ozone that may be produced.

Our invention contemplates the use of air locks in order to introducethe substance to be irradiated into an evacuated radiation chamberWithout destroying the low pressure conditions in that chamber. In thefollowing portion of the specification we shall describe three separateembodiments for carrying out the objects of our invention, namely, theembodiment-shown in Figures 1 to 4; the embodiment shown in Figures 5and 6; and

the embodiment shown in Figures 7 and 8.

Other objects and advantages will become apparent from the followingdescription taken in conjunction with the drawings in which:

Figure 1 is a sectional elevation of an embodiment of the presentinvention;

Figure 2 is a section taken at line 22 of Figure 1;

Figure 3 is an isolated planview of the door used in embodiment ofFigures 5, l and 2;

Figure 4 is a schematic illustration of a control apparatus for use withthe embodiment of Figure 1 through Figure 5 is an elevational view insection of a second embodiment of the invention;

Figure 6 is a section taken at line 6-6 of Figure 5;

Figure 7 is an elevational view in section of a third embodiment of theinvention; and

Figure 8 is a section taken at line 8-8 of Figure 7.

Referring to Figure l a resonant transformer, generally 10, is used as asource of high voltage to accelerate electrons through an evacuatedtube, generally 11, centrally disposed within the transformer. Suchtubes and transformers are well known apparatus, manufactured and soldby electrical equipment companies, e.g., see Nucleonics, vol. ll, No.ll, pages 64-66, November 1953. At the end of tube 11 is a thinstainless steel sheet forming the window 12. The Window is supported bya stainless steel grid 13. The irradiation chamber and air locks areformed within a rectangular casing 14 which has a round tube 15centrally disposed therein. Four movable doors 16 through 19 are used todivide tube 15 into an entrance air lock 20, a radiation chamber 21 andan exit air lock 22. Concrete or other shielding material is used aboutthe radiation chamber 21.

Four fluid cylinders, in this case air cylinders, 23 through 26 are usedto move doors 16 through 19 re spectively. Referring to Figures 2 and 3it will be seen that door 17 is attached to an operating rod 27 whichactually is an extension of the piston rob 28 of air cylinand appliesair pressure from source 86 through pipe 91 and pipe 93 to the oppositeend of cylinders 23 and 25. This returns the doors 16 and 18 to theirclosed position. After doors 16 and 18 have closed switch 80 opens tode-energize solenoid 107 and permit fourway valve 106 to repositionitself. When this is done, valve 106 applies vacuum through pipe 168 toentrance lock 20 and exhausts outlet lock 22 through pipe 109 andexhaust pipe 110 to atmosphere.

After a time sufiicient to permit vacuum source 100 to evacuate entrancelock 20 to the desired pressure, switch 76 opens and switch 77 closes,so that a check of the vacuum in entrance lock 20 is made by vacuumregulating switch 1434. If the vacuum has been drawn to the desiredpressure, the apparatus continues to run and switch 77 opens with switch76 closing at the same time. Switch 79 now closes to energize solenoid99 and reposition fourway valve 88. This applies air pressure from pipe91 to pipe 94 and exhausts pipe 95 to atmosphere through pipe 97. Thechange of air pressure on cylinders 24 and 26 opens doors 17 and 19. Theopening of door 17, allows the carrier 47 in entrance lock 2% to dropinto irradiation chamber 21 and the opening of door 19 permits thecarrier 47 in outlet lock 22 to drop on to discharge conveyor 60. Switch79 then opens to de-energize solenoid 90 to position valve 88 so thatcylinders 24- and 26 will close doors 17 and 19 respectively.

While carrier 47 with the product to be irradiated is in the irradiationchamber, switch 81 closes to actuate transformer so that a voltage willbe appdied to tube 11 to emit electrons therefrom. The electrons willbomhard the product within the carrier. Prior to the carrier 47 beinginserted into the entrance lock 20, clock motor 58 was wound so thatduring the period of time the carrier is passing through the two locksand the irradiation chamber supporting plate 57 is rotating and turningthe product with it. Thus the product will be bombarded from all sidesby the electrons from tube 11 during the period of time that transformer10 is energized.

Following the closing of doors 17 and 19, switch 8% is closed toenergize solenoid 107 repositioning fourway valve 106. This evacuatesoutlet lock 22 and applies air pressure to inlet lock 29. After a checkis made of the extent of evacuation of outlet lock 22 through vacuumregulating switch 104, switch 78 closes to energize solenoid 89 andreposition fourway valve 87. As previously described this opens doors 16and 18 to permit product to be inserted with a carrier into the entrancelock 26' and to permit the carrier 47 in the irradiation chamber 21 todrop into the outlet lock 22. The described cycle continues with productalways being inserted at the top into entrance lock 20 and dropping fromthe bottom through outlet lock 22.

It will be noted that at no time are any of the doors leading to theirradiation chamber 21 opened until the pressure on the air lock side ofthat door has been reduced to the desired pressure in the irradiationchamber. Similarly doors 16 and 19 are not opened except after thepressure within the respective locks has been raised to the pressureexisting outside of the apparatus. With respect to each of the doors, aseal is maintained around the door by the pressure diiferential on the0pposite sides of the doors. This pressure differential presses the dooragainst the gasket on the low pressure side so as to obtain a good sealaround the door. If

little or no pressure differential exists on opposite sides of thedoors, there is little or no necessitity for maintaining any seal aboutthe door and the fact that the pressure difierential will not hold thedoor tight against the gasket is then unimportant. It is to beremembered that no door is opened before the pressure on opposite sidesthereof has been equalized. Before a door is withdrawn thepressure inthe chest 29 through 32 associated with the particular door that isbeing opened either will have .ation chamber 21.

been reduced to the pressure exis ing on he opposite sides of the doorto be opened by leakage through the gaskets associated with the do r, orif s fli i le k does not occur around the gaskets to change the pressurewithin the chest to that existing on both sides of the door, the gaskets37 and 38 will provide a seal for the period of time that the door isopened to prevent any change in pressure on the inside of tube 15resulting from a different pressure existing within the chest into whichthe door is drawn.

When product is being passed through the apparatus which has little orno moisture content, it may be possible to completely eliminate the useof any window 12 on irradiation tube 11. In such a case the vacuum drawnby the sources and 101 should be sufliciently great to provide thedesired vacuum within the vacuum tube 11. Normally in such a case, afilter to remove any moisture from the air used to pressurize chambers20 and 22 will be connected to exhaust pipe of fourway valve 106, afilter will not be necessary where the ambient humidity conditions arelow. If a sufficiently pow.- erful vacuum source is used, it may bepossible to combine the two vacuum sources 100 and 101. We prefer to usetwo separate sources so as to prevent any possibility of reducing thevacuum in the irradiation chamber 21 at the time that the adjacent locksare first evacuated. The initial load on the vacuum source 100 when itis first connected to a pressurized lock to evacuate that lock isrelatively high and if a sufficiently strong vacuum source is notsupplied, the effect might be to reduce the amount of vacuum inirradiation chamber 21 during the initial period when one of the locks20 or 22 was being evacuated from the ambient pressure.

Another modification would lie in the elimination of the vacuum controlswitch 104, If the vacuum source 1% is sufiiciently strong so that onecould be sure that the lock to be evacuated would be positivelyevacuated during the time cycle provided by the operation of motor 65,there would be no necessity for checking vacuum in the locks before theywere placed in communication with the irradiation chamber by theopenings of the communicating door. Also the control switch 81 whichcontrols the operation of the high voltage transformer 10 can beeliminated with the transformer 10 being energized during all of thecomplete cycle. This would tend to be wasteful but in some types'ofequipment where a warm up period is necessary it might be desirable tooperate the irradiation equipment all the time rather than to take thetime for the electron irradiation equipment to reach its optimumperformance. Various modifications of the carrier 47 will be apparent tothose skilled in the art. With some types of product to be irradiated itmay not be necessary to rotate the product. In this case the supportingplate 57 and cloclgwork motor 58 could be despensed with. As suggestedby the prior art, more than one radiation tube 11 directed into theradiation chamber may be used to accomplish the same result as is doneby rotating the product. In many instances it will be desirable toeliminate the wire mesh 55 employed in the described embodiment toprevent the product from falling out of the carrier.

Another obvious modification would be to change the sequence ofoperation. In the described embodiment doors 16 and 18, and 17 and 19,were opened simultaneously. The cycle could be changed so that doors 16and 19 were opened simultaneously with a carrir being inserted in theentrance lock 20 and another removed from the exit lock 22 at the sametime. After both doors 16 and 19 were closed and both the locks 29 and22 were reduced to the pressure of the irradiation chamber 21, door 18could be opened to drop a carrier 47 from the irradiation chamber 21tothe outlet lock 22. Door 18 is then closed and door 17 would be openedto drop the carrier 47 from the input lock 20 into the irradi- Door 1 7would then beclosed and both of the locks 20 and 22 raised in pressureto the ant bient pressure after which the two outside doors 16 and.19'would be opened for the insertion and removal of the carriers.ft; 1. R ferring to theembodiments of Figures and 6 a .frame generally130 includes a cylindrical casing 131 in a bearing 1 41 in frarne139fConcentric grooves forming' races are formed in bottom plates 136 and132 with a plurality of ball bearings 142 being received in the races,supporting the rotatable member 134 in cylindrical casing 131. Annularseals 143 are received in recesses in top plate 135 abouteach of, thewells 137. Top plate 133 and 135' aremachined fiat so as to normallyprevent any air leakage between these plates. The seals 143 willvta'lre'ca're of wear and possibleleakage between the two top plates 133'and 135.

Attached to the bottom end of shaft 140 is the driven member 145 of aGeneva drive. The driving member 1460f the Geneva drive is attached to ashaft 147 which is suitably journaled in frame 130.. Asprocket 148 isattached to s haft147 and is drivenby achain 149 from a sprocket;150 ona shaft 151. -S haftf151 is journaled in frame 130 and carries a bevelgear 152 which is engaged by bevel gear 153 on t he output shaft 154 ofa motor Openings 158 and 159 are provided in top plate 133. Opening 159is for the purpose of access for the removal of product from and theinsertion of product into wells 137 while opening 158 is aligned with aradiation tube 160 powered by a resonant transformer 161. A housing 162seals the space between the end of the tube 160 and opening 158 in plate133. 1A first vacuum passageway 163 is cut in the bottom of top plate133 and is positioned so as to come into communication with wells 137just after the wells have moved sufliciently far under top plate 133 soas to no longer be in communication with opening 159 therein. Vacuumpassage-way 163 communicates with a pipe on 164 connected to a suitablesource of vacuum. A second passage-way 165 is v in the bottom side oftop plate 133 and connects with a pipe 166'. Passage-way 165 ispositioned to be in communication with opening 158 and with the wells137 when the wells are positioned under tube 160 at which time'the wellforms a radiation chamber. Pipe 166 connects to a suitable source ofvacuum for providing the low pressure in the radiation chamber tobalance the low pressure in radiation tube 160. A third passageway 167is cut in the-underside of top plate 133 extending back from the edge ofopening 159 so as to provide the gradual release of the vacuum withinthe wells 137 as they move towards opening 159. 7

If desired a set of shelves 170 mounted on adjustable brackets 171"maybe provided within wells 137 so as 'to position various sizeslofproducts within the wells.

It is desirable'to havethe'producusuch as'the packages 172,positioned'as closely as possible to the end of through pipes 164 and166 and transformer 161 energized. apackage of product 172 is placed ineach well "as that well appears under cutout 159 in plate 133. The

Geneva. drive of the'power means turns the rotatable 'member134 a'stepjat a time in the direction indicated by arrow 175. As each-well 137moves from beneath the cutout 159 and the top thereof is sealed by topplate 133. The well comes into communication with pas sage way 163 whichevacuates the well. Thus the well at this position serves as" anentrance lock to the radiation chamber. With the next step of movementof the Geneva drive the well moves under tube 160 and the product 172 isradiated by the electro'ns from tube 160. At this position the'wellforms a radiation chamber. Preferably a vacuum check switch such asswitch 104 illustrated in Figure4 isconnected in pipe 164 to make surethat an adequate amount of vacuum is drawn on'the well at the time it isin the entrance lock position and before it moves to the radiationchamber position.- If adequate vacuum is not drawn, the switch willde-energi'ze motor to' prevent an inordinate rise in pressure in theradiation chamber below tube 160.

With the next step of movement of the Geneva drive, the well 137 movesfrom below tube to a position opposite the entrance lock position. Atthis latter position the well forms the outlet lock. With the fourthstep of movement of the Geneva drive the well 137 comes intocommunication with passage-way 167 which gradually reestablishes theambient pressure within the chamber. The chamber continues to move intothe position illustrated in Figure 6 where it is completely below cutout 159. At this latter position the irradiated product may be removedfrom the well 137 and a new package of productinserted therein.v

The embodiment of Figures 7 and 8 illustrate a modification. in whichthe product is moved out and in through the same lock. ,In other words,only one lock is used both to insert product and .remove the productfrom the radiation chamber. In this embodiment the frame generally formsa rectangular casing which is divided by doors 181 and. 182 into'a lock183 a radiation chamber 184. At the bottom side of the .frame 180 are apair of chests 185 and 186 to receive doors 131 and 182 respectively. Inthis embodiment the chests 185 and 186 are sufficiently large to receiveair cylinders 187 and 188 so that no stufiing boxes are needed otherthan those normally on an air cylinder. Carts'189 having a plurality ofwheels 190 are used to carry the product 191 to be irradiated into andout of radiation chamber 184. j

A pair of tracks 192 spaced to fit the wheels 190 of carts 189 are usedoutside the chamber to rollthe carts into lock 183. At the end of eachof tracks 192 is .a bridge 193 pivotally connected to track 192. Aspring 194 connecting bridge 193 and track 192 normally urges the bridgeinto the upward position shown in the drawings. Similarly within lock183 are a pair'of tracks 195 supported from the walls of frame 180 bybrackets 196. Bridges 197 pivotally attachedto tracks 195 are urgedupwardly by springs 198. Within radiation chamber 184 a pair of tracks199 are secured to a cross member 28%), which cross member is attachedto the piston rod 201 of an air cylinder 202. Air cylinder 202 isremember 211 is permitted to pivot forwardly with respect to bar1209 butnot to turn backwardly from the vertical position. To transfer the carts189 from radiation chamber 184 back into lock 183 an air cylinder 215 isused'which is mounted in a well 216 in the wall of frame 180. The pistonrod 217 of cylinder 215 carries a pusher'218 on the end' thereof. A cutout219is provided in the bottom wall of frame 180 to. receive the.tracks 199 and cross member 200 as they are, lowered by air cylinder 202to a position, at which the tracks. are level with the bottom floor ofthe air lock 183. Pipe 225 connects radiation chamber 184 with asuitable source of vacuum and pipe 226 connects lock 183 with a.suitable source of vacuum through a control valve corresponding to thatillustrated at 104 in Figure 4. The control apparatus for the embodimentmay consist of parts corresponding to those described in connection withFigure 4 with their connections being suitably modified to carry out thesequence of operations hereinafter described.

In operation the radiation chamber is evacuated and the power source,not shown, feeding electron tube 205 energized. With the doors allclosed and lock 183 at atmoshperic pressure, fluid cylinder 187 isactuated to open door 181. A cart 189 carrying product is pushed by handfrom tracks 192 into lock 183' and onto tracks 195. The movement of thecart lowers bridges 193 against the resistance of springs 194. After thecart has passed into the lock 183, the springs 194 will raise bridges193. As the cart passes pusher 211, this pusher is pivoted forwardlyagainst the resistance of springs 212. As soon as the cart has passedbeyond pusher 211, spring 212 returns the pusher 211 to the positionillustrated in Figure 7. After door 181 is closed, a vacuum is appliedto the lock 183 through pipe 226 and the pressure is reduced to apressure equaling that in the radiation chamber 184. At this time aircylinder 188 is energized to open door 182. When door 182 is firstopened, tracks 199 are lowered to be received in recesses 219. Aircylinder 215 is energized and pusher 218 moves a cart 189 from tracks199 into the bottom of lock 183. After the retraction of pusher 218, aircylinder 202 raises track 199 to the position illustrated in Figure 7.Subsequently air cylinder 208 is actuated to move pusher 211 to theright in Figure 7 and move the cart from tracks 195 onto the tracks 199.During this movement bridges 197 are lowered against the resistance ofsprings 198. The springs return the bridges to the upright positionafter the cart has moved into the radiation chamber. Pusher 211 is thenretracted and door 182 is closed. The product 191 in the cart in theradiation chamber 184 is bombarded with electrons from tube 205. Lock183 is returned to atmospheric pressure and door 181 is opened. If acart is in the bottom of lock 183, it is drawn out of the lock. A newcart with product thereon is rolled from tracks 192 onto tracks 195 aspreviously described.

The foregoing detailed description of the specific embodiments is onlyfor clearness of understanding and for the purpose of complying with 35U.S.C. 112 and we do not desire to be limited to the exact details ofconstruction shown and described for obvious modifications will occur toa person skilled in the art. For example, various other types ofradiation equipment could be used (see Nuclear Radiation Physics, byLapp and Andrews, Printicc-Hall, Inc, published l948, particularlychapter 12). The electron tubes described could be powered by a Van deGraaff generator or by a capacitron (see Patent 2,429,217). A linearaccelerator could be used for the production of electrons, etc.

We claim:

' 1. Apparatus for the irradiation of a substance including a radiationchamber, a radiation source including an evacuated radiation tube havingan end within said chamber, vacuation means connected to said chamber tomaintain said chamber at a reduced air pressure to substantially balancesaid evacuation of said tube at said end, air lock means associated withsaid chamber, and conveyor means associated with said chamber and saidlock means to move the substance to be irradiated into and out of saidchamber without substantially raising the air pressure in said chamberwhereby said balance will be maintained.

2. Apparatus for the irradiation of a substance. includ' ing a radiationsource having an evacuated radiation tube having an. end, means toevacuate the space aboutsaid end of said tube to substantially theevacuation pressure of said tube, substance carrier means, chamber meansdefining a confined space about said substance, means associatcd withsaid carrier to sequentially vacuate the space about said substance tosubstantially said pressure, move said substance into said space aboutsaid end, move said substance out of said space about said end of saidtube and restore normal air pressure to said space about said substance.

3. Apparatus for the. irradiation of asubstance, said apparatusincluding a. radiation chamber, a source of radiation associated withsaid chamber, means to maintain a reduced air pressure in said chamber,air lock means adjacent said chamber, door means. between said lockmeans and said chamber and between said lock means and the outsidethereof, said vacuation means being connected to said lock means, asubstance carrier receivable within said lock means and within saidchamber, and power means connected to said door means and said vacuationmeans to apply normal air pressure to said lock means, to open the doormeans between said lock means and the outside thereof whereby a carrierwith substance may be inserted into said lock means, to close said opendoor means, to vacuate said lock means, to open the door means betweensaid lock means and said chamber whereby said carrier may be moved intosaid chamber, and to close said open door means,

4. Apparatus for the irradiation of a substance includ ing a tube, fourmovable doors in said tube dividing said tube into three chambers,substance conveyor means to move the substance between said chamberswhen the com.- municating doors are open, a source of radiationassociated with one chamber, vacuating means connected to said threechambers to vacuate said chambers, and power means connected to saiddoors and to said vacuation means to apply normal air pressure to asecond of said chambers, to open the door leading to said second chantber whereby said substance may be inserted into said second chamber, tovacuate said second chamber, to open the door between said first andsecond chamber whereby said substance may be moved from said second tosaid first chambers, to open the door between the first and thirdchambers whereby said substance may be moved from said first to thethird chambers, to close said door between said first and thirdchambers, to apply normal air pressure to said third chamber, andv toopen the door leading to said third chamber whereby said substance maybe removed from said third chamber.

5. Apparatus for the irradiation of substance including a tube, fourmovable doors in said tube dividing said tube into three chambers,substance conveyor means to move the substance between said chamberswhen the communicating doors are open, a source of radiation associatedwith, the middle chamber, vacuation meansconnected to said threechambers to vacuate said chambers, and power means connected to saiddoors and to said vacuation means repeatedly to apply normal airpressure to one and chamber and to vacuate said other end chamber, toopen the outside door of said one end chamber whereby substance may beinserted into said one end chamber, and the door between the middlechamber and the other end chamber whereby substance may be moved fromsaid middle chamber to said other end chamber, to close said open doors,to vacuate said one end chamber and apply normal air pressure to saidother end chamber, to open the door between said one end chamber and themiddle chamber whereby substance in said one end chamber may be movedinto said middle chamber and: the outside door of said other end chamberwhereby substance in said other end chamber may be removed, and to closesaid open doors.

6,. Apparatus for the irradiation of a substance include 11 ing avertical tube, :generally horizontal doors in said tube dividing saidtube into three chambers, a plurality of substance carriers receivablewithin each of said cham bers, guidemeansassociated with said carriersand said tube to align said carriers in said tube, rotatable supportingmeans on the bottom of said carriers, a source of radiation associatedwith the middle chambentvacuation means connected to said three chambersto'ivacuate .said

chambers, and power means connected to said doors and to said vacuationmeans repeatedly to apply normal air pressure to the upper end chamberand to vacuate the lower end chamber, to open the outside door of saidupper end. chamber whereby substance may be inserted into said chamber'and the door between the middle chamber and the lower end chamberwhereby substance may be moved from said middle chamber to said lowerend chamber, to close said open doors, to vacuate said upper end chamberand apply normal air pressure to'said lower end chamber, to openthe'door between the upper end chamber and the middle chamber wherebysubstance in said upper end chamber may be moved into said middlechamber and the outside doorof said lower end chamber whereby substancein said-lower ,end chamber may be removed, and to close said open doors.

7. Apparatus for the irradiation of a substance including a tube, fourmovable doors in said tube dividing said tube into three chambers,substance conveyormeans to 'r'novethe substance between said chamberswhen the communicating doors are open, means associated with saidconveyor means to rotate said substance, a-source of radiationassociated with the middle chamber, vacuation means connected to saidthree-chambers to vacuate said.

chambers, and power means connected to said doors and to said vacuationmeans repeatedly to apply normal air pressure to one end chamber and tovacuate said other end-chamber, to open the outside door of said one endchamber whereby substance may be inserted into said one end chamber andthe door between the middle cham ber and the other end chamberwherebytsubstance may be moved from said middle chamber to said otherend chamber, to close said open doors, to vacuate said' one end chamberand apply normal air pressure to said other end chamber, to open thedoor between said one end chambe'r'and the middle chamber wherebysubstance in said o ne end chamber may be moved into said-middle"chambers, and effective at a second point along said path in saiddirection from said first point to close said cham- "bers, means tovacuate said closed chambers, and a source of radiation including anevacuated radiation tube having a radiation emitting end at a thirdpoint along said path in said direction from said second point, saidclosure means having an opening operative at said third point throughwhich said evacuated chambers are placed in communication with said endof said tube radiation source without destroying the vacuum in saidchambers whereby said'vacuum in said chambers will substantially balancethe evacuation of said tube at said end and said 'end of said tube willnot be subjected to atmospheric pressure.

9.- Apparatus for the irradiation of a substance including a rotatablemember, a plurality of chambers'attached to said member, power meansconnected to said memher" to rotate said chambers along a given path ina given direction, a: a first point along said path, said chambers beingopen for the insertion and removal 6f product, closure m'ea'nsassociated with 'said chambers, and effecthe eta second point along saidpath in said direction from said first point to close said chambers;means to vacuate said' closed chambers, and a source of radiationincluding an ev acuated radiation tubehavin'g a radiation emitting endat a third pointfalo'ngsaid path in said direction from 'said' secondpoint, said closure means having an opening operative at said thirdpoint through which said vacuated' chambers 'are plac'edin communicationwith said end without destroying the vacuum in said chambers wherebysaid vacuum in said chambers will substantially balance the evacuationof said tube at said end and said end of said tubewill not be subjectedto atmospheric pressure. 10. Apparatus for the irradiation of asubstance including a radiation chamber, a radiation source including anevacuated tube having an end within said chamber, means connected tosaid chamber to vacuate said chamber to a given pressure tosubstantially balance saidevacuation of said tube at said end, air lockmeans, carrier means for said substance and having a space about thesubstance, and vacuation means associated with said carrier to reducethe pressure of said space about said substance to substantially saidgiven pressure, said-carrier means being movable through said lockmeans'to transport said substance into said chamber only after saidvacuation means reduces the pressure of said space to substantially saidgiven pressure whereby said balance will be maintained. V

11. Apparatus for the irradiation of a substance, said apparatusincluding a radiation chamber, a source of rai diation associated 'withsaid chamber, means to maintain a reducedair pressure in said chamber,air locli means adjacent said chamber, door means between said lockmeans and said chamber and between said lock means and the outsidethereof, said vacuation means being connected to said lock means, asubstance carrier receivable within said ,lockmeans and within said chamber, power means connected to said door means and said vacuation meansto apply normal 'air pressure ,to said lock means, to open thedoor meansbetween said lock means and the outside thereof whereby a'carrier withsubstance may be inserted into said lock means, to close said open doormeans, tovacuate' said lock means, to open the door means between saidlock'meansand said chamber whereby said carrier may be moved into saidchamber, and to close said open door means, and control means connectedto said power means to .rende r said power means ineifective to open thedoor between said chamber andsaid lock means until the pressure in saidlock means is substantially equal to the pressure in said chamber. 12. Aprocess of irradiating a substance from a radiation source having avacuated tube from which radiation is emitted from one end thereoii saidprocess comprising the steps' of maintaining said end of said tube'at apressure-substantially corresponding to the pressure of said vacuatedtube, vacuating a first space about said substance, subsequentlypositioning said substance adjacent said tube with said end of said tubein said space, irradiating said substance,subsequently moving saidsubstance away from said end of said tube, and subsequently restoringthe normal air pressure to the space about said substance. a 7

13. -A process of radiating a substance from a radiation source having avacuated radiation tube having a radiation emitting end, said processcomprising the steps of maintaining said end of said tube at a pressuresubstantially corresponding to the pressure of said vacuated tube,moving groups of said substance along a given path in a given direction,at a first point along said path vacuating the space about each group aseach arrives at said point, at a second point along saidpath in'saiddirection from said first point aligning each said vacuated group withsaid tube'with'said end of said tube'in said 13 vacuated space andirradiating each group, moving each said irradiated group away from saidtube and restoring normal air pressure to each group after it has beenmoved away from said tube.

14. A process of radiating a substance from a radiation source having aradiation tube maintained at substantially a given pressure, saidprocess comprising maintaining the pressure in the space beyond the endof said tube at substantially said pressure, vacuating the space aboutsaid substance to substantially said pressure, and thereafter placingsaid substance adjacent said end of said tube in alignment with saidtube and in communication with said space beyond the end of said tubewithout substantially changing the pressure in said space beyond the endof said tube.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES High Voltage Engineering Corp., Bulletin E, pages 22-31.

1. APPARATUS FOR THE IRRADIATION OF A SUBSTANCE INCLUDING A RADIATIONCHAMBER, A RADIATION SOURCE INCLUDING AN EVACUATED RADIATION TUBE HAVINGAN END WITHIN SAID CHAMBER, VACUATION MEANS CONNECTED TO SAID CHAMBER TOMAINTAIN SAID CHAMBER AT A REDUCED AIR PRESSURE TO SUBSTANTIALLY BALANCESAID EVACUATION OF SAID TUBE AT SAID END, AIR LOCK